In the devices of the Prior Art, a geared motor is formed by an electric motor comprising a stator and a rotor, in which the rotor shaft is extended by a worm gear driving a toothed wheel actuating a direction reversal mechanism, such as a connecting rod and crank system. The connecting rod, mounted eccentrically on the toothed wheel via an axis, achieves an oscillating movement at the crank integral, during rotation, with the output shaft of the geared motor. This oscillating movement is transformed into a movement of reciprocating rotation at the output shaft which is connected, for example, to a windshield wiper arm bearing a windshield wiper blade or a mechanism for the transmission of movement to the windshield wiper arms.
Similarly, a geared motor is known in which the shaft of the rotor bears two worm gears capable of meshing with two primary pinions, these pinions driving two secondary pinions meshing with the toothed wheel which actuates the direction reversal mechanism referred to above.
As better described in FR-A-2,240,623, the toothed wheel has a variety of recesses which enable the distance between the axis of the wheel and the axis connecting the connecting rod of the direction reversal mechanism to be varied.
Such recesses are provided so that it is possible to vary the angle of deflection of the crank and consequently the output shaft driving the windshield wiper system.
It has become apparent that such an arrangement of recesses on the toothed wheel produces a weakening in the strength of the wheel, which has to be capable of withstanding the driving torque of the worm gear and the load moment of the direction reversal mechanism and of the output shaft.
Furthermore, this kind of wheel cannot be adapted to every type of angle of deflection desired for the output shaft.
If fact, it is necessary to use a variety of wheels equipped with recesses in order to be able to adapt the mechanism to the angle of deflection desired.